He was a professor in the mathematics department at the Université de Montréal since 1969. In addition to his teaching duties at that university, he was also an administration staff member and a member of the executive committee.

When the Liberals returned to power in 2003, Gautrin was named the Parliamentary secretary to PremierJean Charest from 2003 to 2005. In 2005, he was named the Online Government Minister and in 2006 the Minister of Governmental Services. After being re-elected in 2007, he was named the Assistant House Leader of the Government and parliamentary assistant to the Premier. He was re-elected in the 2008 Quebec general election.